HARQ process continuation after CQI-only report

ABSTRACT

Techniques for controlling synchronous HARQ retransmissions are disclosed, in which non-adaptive retransmissions scheduled for a first transmission time interval are automatically deferred to a later transmission time interval in the event that a control message prohibiting the retransmission during the first transmission interval is received. In an exemplary method, a NACK message is received in response to a previous data transmission corresponding to a stop-and-wait HARQ process, and a synchronous HARQ retransmission is scheduled for a first transmission interval in response. A control message indicating that data for the stop-and-wait HARQ process may not be sent during the first transmission interval is received, and the synchronous HARQ retransmission is automatically deferred to a second transmission interval, responsive to the control message. An explicit grant is not required to trigger the retransmission during the second transmission interval.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/059,843, which was filed on Feb. 18, 2011, which is anational stage application of PCT/SE2009/050096, filed Jan. 30, 2009,and claims benefit of U.S. Provisional Application 61/089,950, filedAug. 19, 2008, the disclosures of each of which are incorporated hereinby reference in their entirety.

TECHNICAL FIELD

The present invention relates generally to data communications inwireless communication systems, and in particular relates to methods andapparatus for suspending an automatic repeat request (ARQ) process inwireless communication systems using a stop-and-wait ARQ protocol.

BACKGROUND

The 3^(rd)-Generation Partnership Project (3GPP) has developed a set ofstandards for a third-generation (3G) wireless communications systemreferred to as the Evolved-UMTS Terrestrial Radio Access Network(E-UTRAN) or the Long-Term Evolution (LTE) system. Parts of the LTEspecifications define a medium access control (MAC) layer that uses amulti-process, stop-and-wait, hybrid automatic repeat-request (HARQ)protocol for data transmission between the LTE base station (evolvedNode-B, or eNodeB) and a user mobile device (user equipment, or UE).

In LTE and other systems that use multi-process HARQ, each data packetsent from a transmitter to a corresponding receiver is associated withan active HARQ process. The receiving entity provides feedbackindicating successful or unsuccessful reception of the data associatedwith a process and, based on the received feedback, the transmittingentity attempts to perform a retransmission. In LTE systems inparticular, the base station transmits control signaling to provideinformation about the successful reception of (or failure to receive)the data associated with an uplink HARQ process; this control signalingis processed by the physical layer entity at the UE and provided to theMAC layer. If the control signaling indicates a failure to receive thedata associated with a given process, the MAC layer in turn delivers aretransmission packet to the physical layer.

In LTE systems, the base station generally explicitly assignstransmission resources (one or more OFDM resource blocks, for one ormultiple time intervals) to a terminal for both uplink and downlinktransmissions, and determines the transmission format (modulation andcoding scheme) to be used. For LTE uplink transmissions, HARQretransmissions may be non-adaptive (i.e., using the same transmissionresources and transmission format as used for the originaltransmission), or adaptive (i.e., one or both of the transmissionresources and transmission format are explicitly modified by the basestation). The specifics of each retransmission are controlled based onthe physical layer signaling from the base station to the mobileterminal.

In more detail, an LTE mobile terminal receives uplink grant informationvia the Physical Downlink Control Channel (PDCCH). The grant messagespecifies the HARQ process ID, type of transmission(new/retransmission), redundancy version, etc. ACK/NACK messagescorresponding to the HARQ processes are sent via the Physical HARQIndicator Channel (PHICH). However, an explicit grant for a givenprocess (received on the PDCCH) overrides the ACK/NACK messages, so thatthe ACK/NACK status is ignored if a PDCCH grant is received. As notedabove, a PDCCH grant explicitly specifies the transmission resources andtransmission format, and thus may specify an adaptive retransmission fora given HARQ process.

If a PDCCH message for a given process is not received, then the HARQfeedback (ACK/NACK) is considered. In particular, if a NACK is receivedthen a synchronous non-adaptive retransmission is scheduled for the nexttransmission time interval assigned to that process. If an ACK isreceived, then no non-adaptive retransmission is planned. However, thebuffered data for that HARQ process is preserved until a PDCCH grant forthat process is eventually received. As a result, a subsequent grant mayrequest a re-transmission of the HARQ process data (even if an ACK waspreviously received), or may grant resources for a transmission of newdata for the HARQ process. Those skilled in the art will appreciate thatthe former grant can be viewed as an implicit NACK, while the latter isan implicit ACK. The skilled practitioner will further appreciate thatthis procedure allows for rapid recovery from several signaling errorscenarios, such as ACK-to-NACK and NACK-to-ACK reception errors.

LTE base stations may occasionally request that the mobile terminaltransmit physical layer information, such as channel quality data. Theradio link resources (e.g., in time and frequency) for transmitting suchadditional information elements may be pre-configured or allocateddynamically, e.g., on the Physical Uplink Control Channel (PUCCH). Thebase station may also determine whether the terminal may send only therequested information element(s) in a given transmission time interval,or whether the mobile terminal may multiplex the information elementswith other data, such as the data from a current stop-and-wait HARQprocess. The LTE base station may signal this decision to the terminalusing a dedicated control indicator that is associated with otherphysical layer control information provided by the base station to theterminal. For convenience, this control indicator is called a CQI-onlyindicator in the discussion that follows, although those skilled in theart will appreciate that this indicator (or other flag or indicator) maybe used to indicate the exclusive transmission of other physical layerinformation elements, such as a power headroom report.

If the base station indicates to the terminal that the requestedinformation element must not be multiplexed with data, the terminal mustsuspend an active process if that process has data pending forretransmission, e.g., via a non-adaptive retransmission. Furthermore, amechanism is needed for resuming the pending process at the nextappropriate transmission opportunity. According to a conventionalsolution, upon receiving an indication that only requested informationelements may be transmitted during a transmission time intervalcorresponding to a pending HARQ retransmission, the physical layer ofthe mobile terminal indicates a positive feedback (ACK) to the LTE MAClayer, which in turn suspends the HARQ process. As noted above, the HARQprocess buffer is retained even upon receipt of an ACK, and is flushedonly upon receipt of an uplink grant indicating that new data should besent for that process. Thus, a HARQ process suspended in the mannerdescribed above can be resumed by an adaptive uplink grant indicating aretransmission, i.e., having the same new-data indicator (NDI) value.

This particular mechanism for suspending a HARQ process upon receipt ofa CQI-only indicator may be implemented in two ways. First, the ACKcould be sent by the eNodeB over the PHICH and forwarded by the physicallayer to the MAC layer. Alternatively, the ACK message could be locallygenerated by the physical layer upon reception of an uplink grant for aCQI-only transmission. This latter approach avoids conflicting behaviorof MAC and physical layer in case of errors in receiving the controlsignaling.

However, an obvious drawback of suspending the HARQ process byindicating an ACK is that this approach requires an adaptive uplinkgrant to be sent on PDCCH to resume the uplink transmission. This costsscarce layer 1/layer 2 control signaling resources, and increases errorprobabilities.

Another proposed approach is to configure the base station so that itdoes not prohibit multiplexing of data from a stop-and-wait process ifthere is a pending retransmission. In other words, the base stationavoids sending a CQI-only indicator if there is a pending non-adaptiveretransmission for the corresponding HARQ process. One drawback of thisapproach is that the transmission delay of the information elements maybe increased.

SUMMARY

Disclosed herein are methods and apparatus for controlling synchronoushybrid automatic repeat request (HARQ) retransmissions, in whichnon-adaptive retransmissions scheduled for a first transmission timeinterval are automatically deferred to a later transmission timeinterval in the event that a CQI-only grant is received for the firsttransmission time interval. This approach avoids a complete suspensionof the HARQ process and thus does not require an adaptive uplink grantto be sent to resume the HARQ process. In several of the embodimentsdescribed hereafter, these techniques are completely transparent to theMAC layer, thus simplifying implementation of the MAC protocols.

In an exemplary method, such as might be implemented in a in a wirelesscommunications device having a control circuit configured to implement amedium access control function and a physical layer function, a NACKmessage is received in response to a previous data transmissioncorresponding to a stop-and-wait HARQ process, and a synchronous HARQretransmission is scheduled for a first transmission interval,responsive to the first NACK message. A control message indicating thatdata for the stop-and-wait HARQ process may not be sent during the firsttransmission interval is received, and the synchronous HARQretransmission is automatically deferred to a second transmissioninterval, responsive to the control message. An explicit grant is notrequired to trigger the retransmission during the second transmissioninterval.

The automatic deferral of the synchronous HARQ retransmission to thesecond transmission interval may be performed in several ways. In eachof several embodiments of the present invention, the medium accesscontrol function prepares a retransmission block for the stop-and-waitHARQ process and supplies the retransmission block to the physical layerfunction. The physical layer function determines that the controlmessage prohibits transmission of the retransmission block during thefirst transmission interval, and thus refrains from transmitting theretransmission block during the first transmission interval. In someembodiments, the medium access control function detects that no HARQfeedback corresponding to the retransmission block is received, andschedules the synchronous HARQ retransmission of the transport block forthe second transmission interval, responsive to said detecting. Inothers, the medium access control function is configured to retain HARQfeedback for each process until new feedback for that process isreceived, and detects that the most recent previous HARQ feedbackcorresponding to the stop-and-wait HARQ process is a NACK message, thusautomatically scheduling the synchronous HARQ retransmission of thetransport block for the second transmission interval responsive to saiddetecting. In still others, the physical layer sends a second NACKmessage, corresponding to the first transmission interval, to the mediumaccess control function, triggering the medium access control functionto schedule the synchronous HARQ retransmission of the transport blockfor the second transmission interval in response to detecting the secondNACK message.

In some embodiments, the control message is included in a resource grantmessage that corresponds to the first transmission interval andindicates that only physical layer information elements may betransmitted during the first transmission interval. In some of theseembodiments the resource grant message indicates that only channelquality data may be transmitted during the first transmission interval.In several embodiments, the stop-and-wait process is one of a pluralityof stop-and-wait HARQ processes for an uplink session between thewireless communication device and an LTE Evolved Node-B.

Also described herein are various embodiments of a wirelesscommunication device configured to control synchronous HARQretransmissions according to one or more of the methods described above.Several embodiments comprise a control circuit configured to implement amedium access control function and a physical layer function, whereinthe control circuit is configured to receive a NACK message in responseto a previous data transmission corresponding to a stop-and-wait HARQprocess and to schedule a synchronous HARQ retransmission for a firsttransmission interval, responsive to the NACK message. The controlcircuit in these embodiments is further configured to receive a controlmessage indicating that data for the stop-and-wait HARQ process may notbe sent during the first transmission interval, and to automaticallydefer the synchronous HARQ retransmission to a second transmissioninterval, responsive to the control message. The automatic deferring ofthe synchronous HARQ retransmissions may be performed according to anyof the techniques described above.

Of course, those skilled in the art will appreciate that the presentinvention is not limited to the above contexts, benefits, or specificexamples, and will recognize additional features, contexts, andadvantages upon reading the followed detailed description and uponviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a wireless communication device accordingto some embodiments of the invention.

FIG. 2 illustrates functional elements of an exemplary control circuitaccording to some embodiments of the invention.

FIG. 3 is a flowchart of an exemplary process for controllingsynchronous hybrid automatic repeat request retransmissions in awireless communications device.

FIGS. 4 a, 4 b, and 4 c are flowcharts illustrating exemplary processesfor automatically deferring a synchronous HARQ retransmission from afirst transmission time interval to a second transmission time interval,according to several embodiments of the invention.

DETAILED DESCRIPTION

In much of the discussion that follows, various embodiments and aspectsof the present invention are described in the context of an LTE system.Of course, those skilled in the art will appreciate that the techniquesand apparatus disclosed herein may be applied to or adapted for otherwireless systems, including (but not limited to) Wideband-CDMA, WiMax,and Ultra Mobile Broadband (UMB) systems. Those skilled in the art willalso recognize that the inventive techniques are not limited to use incontrolling uplink (mobile-to-base station) HARQ processes, althoughmany of the illustrative examples provided herein are based on LTEuplink HARQ processing. Indeed, the techniques described herein may beapplied to the control of downlink (base station-to-mobile) ARQprocesses as well as to ARQ processes between peer devices in apeer-to-peer wireless communication system.

The use of the term “exemplary” is used herein to mean “illustrative,”or “serving as an example,” and is not intended to imply that aparticular embodiment is preferred over another or that a particularfeature is essential to the present invention. Likewise, the terms“first” and “second,” and similar terms, are used simply to distinguishone particular instance of an item or feature from another, and do notindicate a particular order or arrangement unless the context clearlyindicates otherwise.

FIG. 1 is a block diagram of an exemplary wireless communications device100 according to some embodiments of the present invention. Wirelessdevice includes radio circuits 110, coupled to antenna 115 and controlcircuit 120, which in turn is coupled to input/output (I/O) devices 160.Control circuit 120 comprises a central processing unit 130, memory 140,and other control circuitry 150. Control circuit 120 executes theprogram code 145 stored in memory 140, using CPU 130, therebycontrolling the operation of the wireless communications device 100. Thewireless communications device 100 receives signals input by a user andoutputs images and sounds through the I/O devices 160, which may includea keypad, microphone, one or more displays, speakers, and the like.Radio circuits 110 are configured to receive and transmit wirelesssignals, delivering received signals to the control circuit 120 andoutputting signals generated by the control circuit 120 to the antenna115 for transmission. Control circuit 120 and radio circuits 110 may beconfigured to operate according to one or more wireless communicationstandards, such as according to the LTE specifications promulgated bythe 3^(rd)-Generation Partnership Project (3GPP).

Of course, the block diagram of FIG. 1 is simplified; a number offeatures and elements not necessary to a complete understanding of thepresent invention are omitted. Those skilled in the art will appreciatethat the control circuit 120 may comprise one or severalmicroprocessors, microcontrollers, digital signal processors, and thelike, each of which may be configured with appropriate software and/orfirmware, and may further comprise various digital hardware blocksconfigured to carry out various signal processing tasks. Control circuit120 may be implemented with one or more application-specific integratedcircuits (ASICs), off-the-shelf digital and analog hardware components,or some combination of ASICs and off-the-shelf hardware. Memory 140 mayinclude several different types, including, but not limited to, flash,read-only memory (ROM), random-access memory (RAM), cache memory, etc.,and may be implemented completely or partially on-board one or moreASICs, or using memory devices separate from CPU 130 and other controlcircuitry 150, or with some combination of these approaches.

Viewed from the perspective of a communications protocol framework, theradio circuits 110 embody a portion of Layer 1 (the physical layer, or“PHY” layer), while the control circuit 120 embodies the remainder ofLayer 1 as well as functions of Layer 2 (data link layer) and Layer 3(network layer). This can be seen in FIG. 2, which illustrates thefunctional elements of an exemplary control circuit 120. Thus, controlcircuit 120 embodies an application layer 210, a network layer 220, anda radio link control (RLC) entity 230, each of which may be configuredto operate according to one or more conventional communicationsstandards. Control circuit 120 further embodies a medium access control(MAC) function 240, which is coupled to a physical layer controlfunction 260. Those skilled in the art will appreciate that each of theillustrated functional elements of control circuit 120 may beimplemented by means of CPU 130 (or other processor or processors)executing program code 145, or using one or more appropriatelyconfigured hardware blocks, or some combination thereof.

Those skilled in the art will further appreciate that the RLC entity 230and MAC function 240 are typically viewed as corresponding to Layer 2 ofthe Open System Interconnection (OSI) model. RLC entity 230 providessegmentation, reassembly, concatenation, padding, retransmission,sequence check, and duplication detection on transmitted data or controlinstructions, depending on transmission quality requirements. Amongother functions, MAC function 240 multiplexes packets received fromdifferent logical channels of the RLC entity 240 to common, shared, ordedicated transport channels according to radio resource allocationcommands and transmission format information managed by scheduler 250,and de-multiplexes transport blocks received from the physical layer 260to the appropriate RLC logical channels.

Of course, the detailed operation of the RLC entity 230, MAC function240, and PHY layer control function 260 will vary depending on thestandard or standards supported by a given wireless communicationdevice. Details of the 3GPP LTE requirements for operation of the PHYand MAC layers are given in the 3GPP documents: “3rd GenerationPartnership Project; Technical Specification Group Radio Access Network;Evolved Universal Terrestrial Radio Access (E-UTRA) Medium AccessControl (MAC) protocol specification (Release 8)”, 3GPP TS 36.321, and“3rd Generation Partnership Project; Technical Specification Group RadioAccess Network; Evolved Universal Terrestrial Radio Access (E-UTRA);Physical Layer Procedures (Release 8)”, 3GPP TS 36.213, respectively. Anoverall description of the LTE radio access network is provided in “3rdGeneration Partnership Project; Technical Specification Group RadioAccess Network; Evolved Universal Terrestrial Radio Access (E-UTRA) andEvolved Universal Terrestrial Radio Access Network (E-UTRAN); Overalldescription; Stage 2 (Release 8)”, 3GPP TS 36.300.

As discussed above, an LTE base station sends feedback to the mobileterminal in response to each uplink data transmission, indicating thesuccessful or unsuccessful reception of the data associated with thecorresponding HARQ process. As seen in FIG. 2, the mobile terminalmanages a plurality of HARQ processes 247, using HARQ entity 245. If theeNodeB could not correctly decode received data for the process, itsends a negative acknowledgement (NACK) using physical layer controlsignaling. Once the physical layer entity 260 at the mobile terminaldelivers this NACK to the MAC layer 240, the MAC layer 240 prepares asynchronous non-adaptive retransmission for the HARQ process 247, anddelivers the corresponding data to the physical layer 260 fortransmission.

In the meantime, however, the base station may have decided to requestan information element such as a channel quality information report fromthe terminal. Due to limited transmission resources it may in some casesdecide to suspend the pending HARQ non-adaptive retransmission. It doesthis by requesting a so-called CQI-only report, which prohibits theterminal from multiplexing the channel quality information report withthe pending retransmission data. As explained above, this indicator isalso transmitted using physical layer control signaling and it isreceived and processed by the physical layer entity 260 in the mobileterminal.

In various embodiments of the invention, the received feedback(ACK/NACK) is passed from the physical layer 260 to the MAC layer 240regardless of whether information elements have been requested andregardless of whether multiplexing of the requested information elementswith HARQ process data is permitted. As a result, the MAC layer 240 willprepare a synchronous non-adaptive retransmission for a particular HARQprocess 247 if a NACK corresponding to that process is received (and ifno adaptive retransmission is signaled via a PDCCH grant message.) Theretransmission block prepared by the MAC layer 240 is then delivered tothe PHY control layer 260 for transmission, as per the “normal” case.However, in these embodiments the PHY control layer 260 discards theretransmission block when transmission is prohibited by multiplexingconstraints. This approach hides the multiplexing constraints from theMAC layer 240. To avoid the need for a grant message signalingresumption of a suspended HARQ process, control circuit 120 isconfigured to automatically defer the synchronous non-adaptiveretransmission to a later interval. Thus, the HARQ retransmission ismerely deferred in response to a conflict between the non-adaptiveretransmission and receipt of a CQI-only message, and not fullysuspended.

The deferred retransmission attempt may be triggered in a number ofdifferent ways. In some embodiments, the MAC layer 240 may be configuredto detect that HARQ feedback was not received for a given retransmissionattempt (because the PHY layer 260 discarded the retransmission block),and to automatically re-schedule a non-adaptive retransmission for thenext transmission time interval for the corresponding HARQ process 247.In other embodiments, the physical layer entity 260 is modified so thatit stores the NACK message received in response to the earliertransmission (i.e., the NACK message that triggered the firstretransmission attempt) and delivers it to the MAC layer 240 upon thenext transmission opportunity for the corresponding process. In theseembodiments, the MAC layer 240 remains unaware that the previousretransmission block was not actually transmitted by the physical layer260, since it simply detects a NACK in response. Alternatively, the MAClayer 240 may be specified in a way so that it retains the most recentlyreceived ACK/NACK message for each HARQ process 247 and so that the HARQentity 245 prepares re-transmissions for a pending process once eachround trip time if the last received feedback was a NACK. With each ofthese approaches, the impact to the MAC layer 240 is minimized, or eveneliminated entirely.

FIG. 3 is a process flow diagram illustrating generally a method forcontrolling synchronous HARQ retransmissions in a wireless communicationdevice. The pictured method, which is a generalization of the techniquesdescribed in detail above, may be implemented using a control circuitconfigured to implement a MAC function and a physical layer function,such as the control circuit 120, MAC function 240, and physical layercontrol function 260 discussed above. However, those skilled in the artwill appreciate that the process pictured in FIG. 6 may be implementedin devices configured for operation in wireless networks other than LTE,and is not limited to application in mobile terminals.

In any event, the method illustrated in FIG. 3 begins with thetransmission of a transport block corresponding to a given stop-and-waitHARQ process, as shown at block 310, and the receipt of a NACK message,in response. In the usual case, the NACK message is received from theremote node, and indicates that the remote node was unable tosuccessfully decode the transport block. However, those skilled in theart will appreciate that some wireless devices may be configured tolocally generate a NACK message under some circumstances, such as if atransmission conflicts with a higher priority radio task such as ameasurement task. In either event, however, the MAC layer “receives” aNACK, and may generally remain unaware of whether or not the transportblock was actually transmitted over the air.

In any case, the process illustrated at FIG. 3 continues, as shown atblock 330, with the scheduling of a synchronous retransmission, inresponse to the NACK, for a first transmission time intervalcorresponding to the pending HARQ process. The MAC layer thus prepares aretransmission block and sends it to the PHY layer for transmission.

At block 340, the PHY layer determines whether or not a CQI-only controlmessage (or other control message indicating that data for the HARQprocess may not be sent during the first transmission time interval) hasbeen received. If no such message is received, then the non-adaptiveretransmission is completed, during the first transmission timeinterval, as shown at block 360. If such a message is received, however,then the synchronous retransmission is automatically deferred to asecond transmission time interval, e.g., the next available transmissiontime interval corresponding to that HARQ process.

FIGS. 4A, 4B, and 4C illustrate additional details of three techniquesfor automatically deferring a synchronous HARQ retransmission to asecond transmission interval, responsive to a control message indicatingthat the retransmission may not be sent during the originally plannedfirst transmission interval. Again, any of these techniques may beimplemented in any of the wireless communication devices discussedabove.

Each of the illustrated process flows begins with the preparation of aretransmission block by the MAC layer, in response to a NACK messagecorresponding to an earlier transmission attempt for a givenstop-and-wait HARQ process, as shown at block 410. The retransmissionblock is forwarded to the physical layer for transmission in the firsttransmission time interval, i.e., the next transmission time intervalcorresponding to the HARQ process. Next, as shown at block 420 in eachof the flow diagrams of FIGS. 4A, 4B, and 4C, the physical layerdetermines that transmission of the retransmission block during thefirst transmission interval is prohibited, e.g., by detecting a CQI-onlymessage or other control message(s) requesting information elements andprohibiting the multiplexing of process data with the requestedinformation elements. In response to this message, the physical layerrefrains from transmitting the retransmission block during the firsttransmission interval, e.g., by simply discarding the block.

As noted earlier, the MAC layer in some embodiments of the invention maybe configured to detect the absence of HARQ feedback corresponding tothe retransmission attempt, and to automatically re-schedule theretransmission for the next appropriate time interval in response tothis detection. This approach is shown at block 430 of FIG. 4A. In somealternative embodiments, the MAC layer is instead configured to retainthe most recent HARQ feedback for each HARQ process, and to use thisinformation in determining whether another retransmission attempt isrequired. This approach is illustrated at block 440 of FIG. 4B. Thus,when preparing for the second transmission time interval, whichcorresponds to the pending HARQ process, the MAC layer determines thatthe most recent previous HARQ feedback corresponding to thestop-and-wait HARQ process is a NACK message, and automaticallyre-schedules another HARQ retransmission of the transport block for thesecond transmission interval. As suggested above, the MAC layer need notbe aware that the stored NACK message was originated in response to theoriginal transmission attempt (i.e., at block 310 of FIG. 3), ratherthan in response to the earlier retransmission attempt (at block 410) atthe first transmission interval.

Yet another approach is illustrated at blocks 450 and 460 of FIG. 4C. Inthis variation, the physical layer, in response to determining that theretransmission attempt in the first transmission interval is prohibited,generates a NACK message corresponding to the retransmission attempt (orretrieves a stored NACK message received in response to the originaltransmission) and sends it to the MAC layer. The MAC layer receives thisNACK message and uses it in preparing for the second transmissioninterval, as shown at block 460. Thus, the MAC layer automaticallyschedules another retransmission attempt for the pending HARQ processfor the second transmission interval.

As noted above, the control message that prohibits transmission of theHARQ process data during the first transmission interval may be aso-called CQI-only message, or other message that indicates that HARQprocess data may not be multiplexed with information elements requestedfrom the physical layer. In some embodiments, this control message maybe included in a resource grant message (e.g., transmitted over the LTEPDCCH) corresponding to the first transmission interval but indicatingthat only physical layer information elements, such as channel qualitydata, may be transmitted during that interval.

Those skilled in the art will appreciate that the techniques describedabove may be applied in various systems that employ one or a pluralityof stop-and-wait processes, and may be used in one direction only, suchas for an uplink session between a mobile terminal and an LTE EvolvedNode-B, or in both directions. Indeed, those skilled in the art willrecognize that the present invention may be carried out in various otherways than those specifically set forth herein without departing fromessential characteristics of the invention. Accordingly, the presentlydescribed embodiments are to be considered in all respects asillustrative and not restrictive, and all changes coming within themeaning and equivalency range of the appended claims are intended to beembraced therein.

What is claimed is:
 1. A method for controlling synchronous hybridautomatic repeat request (HARQ) retransmissions in a wirelesscommunication device having a control circuit configured to implement amedium access control function and a physical layer function, the methodcomprising: scheduling a synchronous HARQ data retransmission from thewireless communication device for a stop-and-wait HARQ process;identifying a conflict between the scheduling of the retransmission andreceipt of a control message requesting the exclusive transmission ofphysical layer information from the wireless communication device; andresponsive to identification of the conflict, automatically deferringthe retransmission from when that retransmission was scheduled, in favorof exclusively transmitting the physical layer information.
 2. Themethod of claim 1, wherein said automatically deferring comprisesautomatically re-scheduling the retransmission irrespective of whetherthe wireless communication device receives an uplink grant for thestop-and-wait HARQ process.
 3. The method of claim 1, wherein saidautomatically deferring comprises discarding a retransmission block forthe retransmission at the physical layer function, rather thantransmitting that retransmission block, the retransmission blocksupplied to the physical layer function from the medium access controlfunction.
 4. The method of claim 3, wherein said automatically deferringcomprises detecting, by the medium access control function, that no HARQfeedback corresponding to the retransmission block is received andre-scheduling the retransmission for the stop-and-wait HARQ process,responsive to said detecting.
 5. The method of claim 3, wherein saidautomatically deferring comprises detecting, by the medium accesscontrol function, that the most recent previous HARQ feedbackcorresponding to the stop-and-wait HARQ process is a NACK message andre-scheduling the retransmission responsive to said detecting.
 6. Themethod of claim 3, wherein said automatically deferring comprisessending a NACK message from the physical layer function to the mediumaccess control function indicating failure of the scheduledretransmission, and, responsive to the medium access control functiondetecting that NACK message, re-scheduling the synchronous HARQretransmission.
 7. The method of claim 1, wherein said schedulingcomprises scheduling the retransmission for a first transmission timeinterval, wherein the control message requests the exclusivetransmission of physical layer information during the first transmissiontime interval, and wherein said automatically deferring comprisesautomatically deferring the retransmission until a second transmissiontime interval.
 8. The method of claim 1, wherein the control message isincluded in a resource grant message indicating that only physical layerinformation elements shall be transmitted during a particulartransmission time interval, the particular transmission time intervalconflicting with a transmission time interval during which theretransmission is scheduled.
 9. The method of claim 8, wherein theresource grant message indicates that only channel quality data may betransmitted during the particular transmission interval.
 10. The methodof claim 1, wherein the stop-and-wait HARQ process is one of a pluralityof stop-and-wait HARQ processes for an uplink session between thewireless communication device and an LTE Evolved Node-B.
 11. A wirelesscommunication device comprising a control circuit configured toimplement a medium access control function and a physical layerfunction, wherein the control circuit is configured to: schedule asynchronous HARQ data retransmission from the wireless communicationdevice for a stop-and-wait HARQ process; identify a conflict between thescheduling of the retransmission and receipt of a control messagerequesting the exclusive transmission of physical layer information fromthe wireless communication device; and responsive to identification ofthe conflict, automatically defer the retransmission from when thatretransmission was scheduled, in favor of exclusively transmitting thephysical layer information.
 12. The wireless communication device ofclaim 11, wherein the control circuit is configured to automaticallydefer the retransmission by automatically re-scheduling theretransmission irrespective of whether the wireless communication devicereceives an uplink grant for the stop-and-wait HARQ process.
 13. Thewireless communication device of claim 11, wherein the control circuitis configured to automatically defer the retransmission by discarding aretransmission block for the retransmission at the physical layerfunction, rather than transmitting that retransmission block, theretransmission block supplied to the physical layer function from themedium access control function.
 14. The wireless communication device ofclaim 13, wherein the control circuit is configured to automaticallydefer the retransmission by detecting, using the medium access controlfunction, that no HARQ feedback corresponding to the retransmissionblock is received and re-scheduling the retransmission for thestop-and-wait HARQ process, responsive to said detection.
 15. Thewireless communication device of claim 13, wherein the control circuitis configured to automatically defer the retransmission by detecting,using the medium access control function, that the most recent previousHARQ feedback corresponding to the stop-and-wait HARQ process is a NACKmessage and re-scheduling the retransmission responsive to saiddetection.
 16. The wireless communication device of claim 13, whereinthe control circuit is configured to automatically defer theretransmission by sending a NACK message from the physical layerfunction to the medium access control function indicating failure of thescheduled retransmission, and, responsive to the medium access controlfunction detecting that NACK message, re-scheduling the synchronous HARQretransmission.
 17. The wireless communication device of claim 11,wherein the control circuit is configured to schedule the retransmissionby scheduling the retransmission for a first transmission time interval,wherein the control message requests the exclusive transmission ofphysical layer information during the first transmission time interval,and wherein the control circuit is configured to automatically defer theretransmission by automatically deferring the retransmission until asecond transmission time interval.
 18. The wireless communication deviceof claim 11, wherein the control message is included in a resource grantmessage indicating that only physical layer information elements shallbe transmitted during a particular transmission time interval, theparticular transmission time interval conflicting with a transmissiontime interval during which the retransmission is scheduled.
 19. Thewireless communication device of claim 18, wherein the resource grantmessage indicates that only channel quality data may be transmittedduring the particular transmission interval.
 20. The wirelesscommunication device of claim 11, wherein the control circuit isconfigured to maintain a plurality of stop-and-wait HARQ processes foran uplink session between the wireless communication device and an LTEEvolved Node-B.